Heat oil in a kadai and add mustard seeds followed by jeera and haldi. Then add the finely chopped garlic.
Saute and add the finely chopped onions and green chillies, saute well for few mins.
Add finely chopped tomatoes at this stage and mix well. Cook for 3 mins and add cooked moong dal.
Add salt and let it cook for 3 mins.
Remove from flame and add the juice from half lemon. Garnish with fresh coriander leaves and curry leaves.
This goes well with chapathi and poori.

You can do variation too by adding grated carrot or cooked and mashed potatoes.